For example:
A Grammar of the English Tongue: with the Arts of Logick, Rhetorick,
Poetry, &c. Illustrated... by John Brightland - 1759 - 300 pages

Page 36 - Consonants are divided into Mutes and Liquids call'd also
Half-Vowels; the Mutes are b, c, d, f, v, g, j, k, p, q, t, and are
so call'd because a Liquid cannot be sounded in the same Syllable
when a Vowel follows it, as (rpo).

that page has a poem to help you remember them:

The Consanants we justly may divide
Into Mutes, Liquids, Neuters; and beside
We must for double Consonants provide.
Eleven Mutes Grammarians do declare,
And but four Liquids, l, m, n, and r.
Behind the Mutes the Liquid gently flow
Inverted, from the Tongue they will not go.